This invention relates to lanthanide halide catalysts.
In the polymerization of alpha-olefins, it is known to use catalyst systems comprising a transition metal compound and an organometallic compound. It is further known that the productivity of such catalyst systems can generally be improved if the transition metal compound is employed in conjunction with a metal halide, such as MgCl.sub.2. Many of the prior art catalyst systems are relatively low in activity and, as a result, research continues in an effort to improve the catalyst systems with respect to production of olefin polymers.
In addition, these catalysts produce polymers of narrow molecular weight distribution. For many applications, such as extrusion and molding processes, it is highly desirable to have polymers which have a broad molecular weight distribution. Such polymers evidence excellent processability, i.e., they can be processed at a faster throughput rate with lower energy requirements with reduced melt flow perturbations.
It is also highly desirable to produce broad molecular weight distribution polymers directly in a single reactor, without having to blend polymers having different molecular weights and distribution.